In advanced treatment of supply water, wastewater and biochemical effluent, ion exchange and adsorption resin is widely adopted to concentrate organics and inorganics, and then separate them from water so that the objectives of water treatment, such as decolorization, deodorization, softening and removal of trace organics or heavy metals can be obtained. However, the resin ion exchange devices currently used in this field have many defects, such as complicated pretreatment procedures, large resin consumption, large equipment investment and high operating cost; in addition, it is difficult to realize continuous treatment with one single device, and a large amount of resin regeneration fluid is required due to the poor regeneration efficiency. The appearance of a new type of resin makes it possible to overcome these defects. This so-called powder resin refers to a (magnetic) solid material made of acrylic polymer with 75-200 μm in size. It has rich porous structure and ionic groups and therefore bears such functions as electrochemical adsorption and ion exchange simultaneously; many new types of (magnetic) powder resin have smaller particle size, larger specific surface area and better kinetic performance. In practical application, the powder resin is often firstly mixed with wastewater through agitation for a period of time, and then separated from the water so that it can remove the organics and inorganics from the wastewater through exchange and adsorption. Reactors adopting powder resin in water treatment presents such advantages as shorter treatment time, lower consumption of resin, higher anti-pollution performance, longer service life and smaller amount of desorption fluid. But, since the (magnetic) powder resin has smaller particle size and lower relative density, the adoption of traditional fixed beds or suspension beds will cause strong bed resistance, jamming or even break-up of resin particles, and when conducting the backwash procedure, the resin tends to be brought out of the reactor; in addition, as a single fixed bed or suspension bed cannot realize continuous operation of the powder resin, it severely damages the powder resin's performance in water treatment. Therefore, it is of great necessity to develop a new resin reactor that gives full consideration to the properties of the (magnetic) powder resin, such as smaller particle size, lower density and better kinetic performance, so that it can bring the advantages of this new type of resin into full play.
Currently, MIEX® resin and its application method developed by Orica Company of Australia have been extensively used in water treatment. It adopts acrylic strong basic anion exchange resin to separate a variety of anions (including nitrates, sulfates, phosphates, arsenates) and soluble organic pollutants from water by means of mechanic agitation and inclined pipe separation. In China, a hydraulic ejecting magnetic resin reactor developed by Nanjing CEC Environmental Protection Co., Ltd also appeared on the market of advanced water treatment. However, traditional continuous-stirred reactors are used in both cases, which leads to homogeneous distribution of resin within the whole reactor. As a result, in both cases, the consumption of resin is very large and the recovery of resin is difficult. It is of great necessity to develop a new reactor that can overcome these defects.